Trace chemical optical probe

ABSTRACT

New and improved applications of Raman Scattering are disclosed. These applications may be implemented with or without using an enhanced nano-structured surface that is trademarked as the RamanNanoChip™ disclosed in a pending patent. As a RamanNanoChip™ provides much higher sensitivity in SERS compared with conventional enhance surface, broader scopes of applications are now enabled and can be practically implemented as now disclosed in this application. Furthermore, a wide range of applications is achievable as new and improved Raman sensing applications. By applying the analysis of Raman scattering spectrum, applications can be carried out to identify unknown chemical compositions to perform the tasks of homeland security; food, drug and drinking materials safety; early disease diagnosis environmental monitoring; industrial process monitoring, precious metal and gem authentications, etc.

The present patent application is a Continuation patent application ofcommonly assigned pending U.S. patent application Ser. No. 10/987,842entitled “Applications of Raman scattering probes”, filed Nov. 12, 2004.U.S. patent application Ser. No. 10/987,842 is a Continuation in Part(CIP) Application of application Ser. No. 10/852,787 filed on May 24,2004. aapplication Ser. No. 10/852,787 claims a Priority Date of May 27,2003, benefited from two previously filed Provisional Applications60/473,283 and 60/473,287 filed on May 27, 2003, and another ProvisionalApplication 60/520,222 filed on Nov. 17, 2003 by at least one of acommon Applicant of this Patent Application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the methods and systems fordetection of very small amount of trace chemicals by employing lightscattering probes. More particularly, this invention relates to animproved light scattering probes and detection system implemented withhighly sensitive Raman analyzer embodied as RamanNanaChip™ based on anovel process to fabricate a sensing chip with nano-structured noblemetal surface with improved configurations to detect the trace chemicalswith significantly improved detection. sensitivity for wide varieties ofapplications.

2. Description of the Prior Art

Despite the fact Raman detectors have sensitivity down to a level ofsingle molecule detection (SMD), due to several technical difficulties,conventional Raman sensors still have very limited applications.Specifically, one of the major limitations of Raman spectroscopyapplication is the weak Raman scattering signal for trace chemicaldetection. There are many efforts in attempt to resolve this problem oflow scattering signals in the field of Raman sensing. However, suchefforts still have very limited success and have not been able to makeRaman detectors available for practical and economical applications thaturgently require ultra sensitive chemical trace detections.

It is well known in the art that there is a potential solution byemploying roughened or the nano-structured sensing surface to generatescattering signals of higher intensity. Specifically, thenano-structured materials have found numerous applications in sensing,bioscience, materials science, semiconductor, etc. One of the promisingapplications of sensing technologies with nano-structured materials isSurface Enhanced Raman Spectroscopy (SERS) and Surface EnhancedResonance Raman Spectroscopy (SERRS). It has been discovered that theRaman scattering signal can be enhanced by 10⁴˜10¹⁴ times when moleculesare adsorbed on a nano-structured noble metal (such as Ag, Au and Cu,but not limited to Ag, Au and Cu) surface compared to normal Ramanscattering. Specially, Raman scattering signal gets remarkably enhancedif the surface nanoparticles are isolated. The enhancement is determinedby several factors, among them, the dimensions of the nano-particles andthe distance among these nanoparticles on the surface are veryimportant. It is found that as the scale of these nanoparticlesdecreases, the signal enhancement of Raman scattering increases.Further, as the distance between neighboring nanoparticles islandsvaries, the enhancement effect of Raman scattering also varies. However,the conventional technologies, for example, VLSI lithography technology,are still encountered with technical difficulties to fabricatenano-structure surfaces with reduced dimensions of the nano-particlesand reduced distance among these nano-particles on the surface toachieve scattering signal enhancement.

The very limited availability of non-contaminated nano-structured noblemetal surface is still a major difficult faced by those of ordinaryskill of the art in applying the technologies of SERS (Surface EnhancedRaman Scattering) and SERRS (Surface Enhanced Resonant Raman Scattering)for trace chemical detection. A non-contaminated nano-structured noblemetal surface is required to conveniently deploy in the field formolecular adsorption and subsequent measurement. Due to this limitavailability, even though the detection of trace chemicals can beachieved a part-per-billion (ppb) level, the techniques of applying SERSand SERRS for detecting trace of explosives and/or other chemicalmaterials still have very limited applications.

The technologies of applying SERS and SERRS for detecting tracechemicals were described in many published papers such as “ProbingSingle Molecules And Single Nanoparticles by Surface Enhanced RamanScattering”, Shuming Nie and Steven R. Emory, Science, 1997, 2751102-1106; “Surface Enhanced Raman Spectroscopy of individual Rhodamine6G Molecules on Large Ag Nanocrystals”, Amy M Michaels, M. Nirmal, andL. E. Brus. J. Am. Chem. Soc. 1999, 121, 9932-9939; “Single MoleculeDetection Using Surface Enhanced Ramam Scattering (SERS)”, KatrinKneipp, Yang Wang Harald Kneipp, Lev L. Perelman, Irving Itzkan,Physical Review Letter, 78, 1997. 1667-1670; “Nanosphere Lithography: AVersatile Nanofabrication Tool for Studies of Size-DependentNanoparticle Optics”, Christy L. Haynes and Richard P. Van Duyne, J.Phys. Chem. B 2001, 105 5599-5611.

However, these publications do not provide an effective method toproduce and package the non-contaminated nano-structured noble metalsurface to achieve field applications of SERS and SERRS for tracechemical detection. Furthermore, none of these publications providemethod to fabricate nano-structured materials with well-controlled nanoarray that have reduced and optimized dimensions of the nano-particlesand reduced and optimized distances among, these nano-particles on thesurface to achieve scattering signal enhancement.

The Raman Nano Chip, e.g., a RamanNanoChip™ submitted by the Applicantof this invention for a Trademark Registration, disclosed in aco-pending, application Ser. No. 10/852,787 provides solution to formNano structure sensing surface with high sensitivity. With suchnano-structured surface now available to provide high detectionsensitivity with much improved intensity of detection signals,tremendous potentials for wide varieties of applications could bepractically implemented. Obviously for those of ordinary in the art,there are ever increasing demands to take advantage of the greatlyimproved nano-structured surface now provided by the invention as thatdisclosed in the co-pending Application so that Raman sensors can bepractically implemented to effectively realize these applications thatare urgently in demand.

Therefore, a need still exists in the art to provide practicalconfiguration for conveniently implement the Raman sensors inapplications to antiterrorism, forensic, medical diagnoses, diseasepreventions, industrial process monitoring, environmental cleaning upand monitoring, food, and drug quality control, etc.

SUMMARY OF THE PRESENT INVENTION

It is therefore an object of the invention to provide new applicationsof Raman Scattering with or without using RamanNanoChip™ disclosed inthe pending patent. These applications can he divided into twocategories that one includes Surface Enhance Raman Scattering in whichRamanNanoChip™ is use and another one includes Raman Scattering, inwhich RamanNanoChip™ may be not required.

Since RamanNanoChip™ provides much higher sensitivity in SERS comparedwith conventional enhance surface, some applications that were notpractical before have now become practically achievable. Because thesignificant improvement in Raman scattering achieved by theRamanNanoChip™ broader scopes of application are now enabled and can bepractically implemented as now disclosed in this application.

Furthermore, a wide range of applications that should be achievable withrelative low Raman sensitivity detections implementing conventionalRaman Scattering were also overlooked and neglected due to lowexpectation of Raman sensing capabilities. New and improved Ramansensing applications are also disclosed in this invention that do notrequire high detection sensitivities and do not require surface enhancedRaman sensing devices such as such RamanNanoChip™ applications. Theembodiments disclosed in this invention thus expand the fields ofapplications for devices that implement Raman scattering sensing,technologies.

In applications of first category, detected trace chemicals aretypically in any phase, such as gas, liquid, solid, which gas can befrom solid with certain value of vapor pressure. The laser beam doesn'tstrike on sample under detection, and the scattering light is notcollected from sample directly neither, that makes the detection to be“remote and non-invasive”. The detected molecules and backgroundmaterials are adsorbed onto the surface of the RamanNanoChip™. Thetrapped molecules have much larger scattering cross section than thatthey, are free in gas, liquid or solid. When laser beam strikes ontrapped molecules, Raman scattering occurs and Spectrograph. and dataanalyzer obtains a Raman Spectrum of molecules. Since every chemical hasits own special Raman spectrum, then one is able to apply this principalas Raman fingerprint to identify unknown chemicals. Such applicationsinclude, but not limited, homeland security to detect trace chemicals ofexplosives, biochemical weapons and illegal drug smuggling; food anddrinking materials safety to detect pesticide residues; early diseasediagnosis; environmental monitoring; industrial process monitoring, andso on.

In applications of the second category, the laser beam will strike onsample under test; the scattering light is collected from sampledirectly. It is normal Raman scattering and no RamanNanoChip™ needed.Such technology is available, but is normally ignored and has not yetbeen implemented in applications include, but not limited toapplications to detect counterfeit merchandise such as milk based powderwith less protein; authentication for gem certification, contentanalyses of medical tablets, and detection of methanol and ethanolcontent in wines.

These and other objects and advantages of the present invention will nodoubt become obvious to those of ordinary skill in the art after havingread the following detailed description of the preferred embodiment,which is illustrated in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C: Basic configuration of Surface Enhance RamanScattering in applications of trace molecules detection using aRamanNanoChip™

FIG. 2A typical design of probe head of Raman Spectroscope

FIGS. 3A and 3B show Schematic diagram of Surface Enhance RamanScattering applications in airport safety using a RamanNanoChip™ forpassenger, luggage, and cargo monitoring, respectively.

FIG. 4 Schematic diagram of Surface Enhance Raman Scatteringapplications in public building, safety using a RamanNanoChip™.

FIG. 5 is a schematic diagram of Surface Enhance Raman Scatteringapplications in environmental monitoring using a RamanNanoChip™.

FIG. 6 shows a Schematic diagram of Surface Enhance Raman Scatteringapplications in food safety using a RamaNanoChip™.

FIG. 7 shows a Schematic diagram of Surface Enhance Raman Scatteringapplications in early disease diagnosis and biomedical detection using aRamanNanoChip™.

FIG. 8 shows a schematic diagram of Surface Enhance Raman Scatteringapplications in quality control in production processing with or withouta RamanNanoChip™.

FIG. 9 is a Schematic diagram of configuration of normal RamanScattering applications in counterfeit merchandise detection drugscreening and non-invasive in-vivo test glucose for monitoring diabetes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Refer to FIG. 1A for a basic configuration of a Raman detector 100 usinga RamanNanoChip™ 105 attached to a probe head 110. As shown in FIG. 1B,a RamanNanoChip™ 105 includes a plurality of nano-sticks 108 as thatdisclosed in the co-pending application Ser. No. 10/852,787 filed on May24, 2004 and implemented in this Patent Application as an expandedSurface Enhance Raman Sensing System. The probe head 110 with aRamanNanoChip™ 105 is placed in a space under monitoring. The probeassembly as shown may includes design features such as a vacuum, pump tosuck air flow into a probe assembly 120 enclosed in a housing structureshown with dotted lines to trap molecules of gas, liquid, and solidpowder for carrying out a Raman scattering detection operation. Anexcitation laser is led by optical fibers 125 from frame of the RamanSpectroscope and laser source 140 shown in FIG. 1C that can be placed incentral office far away from the monitoring field. The probe head 110 ispre-aligned to the RamanNanoChip™ 105. The scattering light is collectedby probe head and propagates to mainframe 150 along collecting fiber130. A Raman spectrum is formed based on collected scattering lightthrough spectrograph in a mainframe 150 that carries out dataacquisition and data analyzer. The Raman spectrum is digitalized andready to compare with database of known interested molecules. An alarmsignal is generated from an alarm signal generator 160 when a thresholdof certain molecules under detection is exceeded.

FIG. 2 shows a typical design of the probe head 110. The probe head 110receives a laser projection from an input laser fiber 125 to passthrough a band ejection filter 170 to pass through a lens group 175-1and l75-2 to project onto RamanNanoChip® 105. A scattering light isprojected back to a group of mirrors 180-1 and 180-2 to pass throughanother band-pass filter 185 and a collimated lens to output from thecollection fiber 130.

FIG. 3A is a schematic diagram to show a configuration of the SurfaceEnhance Raman Scattering application in safety of transportation andother places where a passenger screening is required to monitorpassengers 200-1, 200-2, and 200-3. For passenger screenings the probeassembly 120 with embedded RamanNanoChip® 105 is placed in thepassageway 210. The probes head 120 are connected by fibers to themainframe Raman Spectroscope 150 in office near or far away from it. Theprobe head 120 is aligned to a RamanNanoChip™ surface 105 and they arepackaged together. The passageway tunnel 210 can be forced ventilatedand under little negative pressure and/or little higher temperature toincrease evaporation of harmful materials. If a passenger, e.g.passenger 200-2, carrying explosive materials, harmful chemicals,chemical weapons, bio-chemical weapons, nuclear weapons or narcoticdrugs, few molecules of such materials will volatilize into air thatmolecules are adsorbed onto the surface of a RamanNanoChip™ throughspecially designed sample collection system. The Raman Spectrum will berecorded and compared with database in mainframe at office. As soon asthe harmful materials are detected, early stage alarm signal will betriggered and appropriate security actions can be further processed.

FIG. 3B is a diagram to show application implemented to monitor luggage215 for freight transportation carried by a conveyer 230 to pass throughcargo screening channel 220. The probe assembly 120 with embeddedRamanNanoChip™ 105 is placed around the cargo screen channel 220. Theprobes head 120 are connected with fibers to the mainframe RamanSpectroscope 150 in office near or far away from it. The probe head 120is aligned to the surface of a RamanNanoChip® 105 and they are packagedtogether to detect any explosives, chemical or biochemical weapon, orharmful chemicals enclosed in the luggage 215. This configuration can beimplemented in other applications such as mail stations, railwaystations, custom inspection areas, traffic control zones, etc. Thisconfiguration can be easily implemented to detect gun powders or otherexplosives or hazardous materials.

FIG. 4 is schematic diagram of Surface Enhance Raman Scatteringapplications using a RamanNanoChip® in safety of public buildings 250such as airport, railway or bus stations, ballpark buildings, Federalbuildings, auditoriums, theaters, courthouses, and other publicbuildings. The probe assembly 100 that includes probe head 120 combinedwith a RamanNanoChip™ 10 are distributed in the public buildings orothers protected areas. The probe assemblies 100 are applied to monitormany different molecular substances to provide earlier detection of anydangerous or harmful chemicals enter into the monitor areas. Particularexamples of hazardous material monitoring include, but not limited todetection of explosive materials, chemical or biochemical weaponsincluding anthrax, drugs, and so on.

FIG. 5 is schematic diagram of applying the technology of SurfaceEnhance Raman Scattering using a RamanNanoChip™ to monitor harmfulchemicals released into the environment. The probe assemblies 100 aredistributed around potential pollution source, e.g., a factory 260 oraround highway where great number of automobiles 270 pass through. Theprobe assemblies 100 distributed around the monitored areas generateRaman scattering light that is transmitted to a mainframe spectrumanalyzer 150 to determine the contents and concentration of substancereleased into the environment. The monitoring sample can be, but notlimited, soil, water, lake, river, seashore, well, plants, etc. Thisapplication can be extended to car exhausted gas detection andmonitoring by placing the probe assembly near by car exhausting output.

FIG. 6 is schematic diagram of applying the technology of SurfaceEnhance Raman Scattering using a RamanNanoChip™ to monitor substancesfor inspecting quality and safety of foods. The probe assembly 100 isplaced close to a food item 280,i.e., an apple or different fruits,vegetables or other food items that could be contaminated throughtransportations, food processing,, or even food growth process. Themolecules of residue pesticide or other contaminations are drawn intothe assembly 100. A RamanNanoChip™ is used to detect anv suspect harmfulchemicals contained in the food.

FIG. 7 is schematic diagram of applying the technology of SurfaceEnhance Raman Scattering with or without using a RamanNanoChip™ tomonitor substances for early decease detection and diagnosis. The probeassembly 100 is placed near a patient 290. Research result indicatedthat human breathed air have special chemicals contained, such asalkenes and benzene derivatives, if a person under screening isassociated with disease, such as lung cancer (New Scientists, May 2003).Raman sensing technology is able to fingerprint those chemicals inbreath test the to identify some special diseases such as cancers. Theprobe assembly 100 is placed near the patient for carrying out aphysical examination. The patient blows the outpoured breath-air to theprobe assembly 100. The RamanNanoChip™ in probe assembly receives theinlet air for generating a Raman scattering light corresponding to themolecules contained in the airflow from the patient. The scatteringlights are collected by probe head and sent to mainframe of RamanSpectroscope 150 to generate Raman spectrum. Breath test with Ramansensing technology is to make early disease diagnosis which diseaseincludes, but not limited to lung cancer, breast cancer, stomach cancer,liver cirrhosis, failing kidney, ulcer cancer, etc. In case of testingfluids of human beings, the fluid is dropped on a RamanNanoChip™manually, or Raman sensing device can be designed to connect to toiletfor easy sample collection as smart toilet to timely monitor abnormalsignals for disease and drug detection. This application also includesidentifying and sorting protein, DNA and RNA. All testing samples inabove applications can be placed in contact with a RamanNanoChip® toenhance the sensitivity and intensity of Raman scattering detections.The RamantSensor® can also be applied to other areas, including but notlimited to identify Azhemer's disease, non-invasively test glucose tomonitor diabetes, non-invasive test carotenoids to monitor antioxidantstatus for early cancer screening purpose, and so on.

FIG. 8 is schematic diagram of Raman scattering application inindustrial quality control with or without a RamanNanoChip™. Theapplications include, but are not limited to, the in-line monitoring wetchemical concentration in wet chemical process line, stand-offmonitoring of sealed chemical tanks, remote trace chemical detection,semiconductor wafer defect evaluation, and monitoring of the food, fruitand vegetable storage, etc.

FIG. 9 is schematic diagram of applying the technology of SurfaceEnhance Raman Scattering to identify and screen materials including, butnot limited to detect counterfeit merchandise. The applications mayinclude operations such as food, drug, and medicine screening. In thesecases, a RamanNanoChip™ may or may not be required. The excitation laserdirectly strikes on samples under test. With improvement of the wholesystem, of Raman Spectroscope, new applications that might not beavailable previously are now become practical. The Raman Spectrum ofscattering light from the tested materials shows characteristic contentsthus provide clear indications whether there are illegal additives addedto the commercial merchandises. The potential counterfeit merchandisesuch as milk-based powder, wine, and medical tablets may be placed underthe Raman detector as materials under investigation and screen. Theapplications can be extended to authenticated signatures and currencybills by detecting false signature and false bills by generating Ramanscattering spectrum of the signature and dollar bills and compare thesespectrum with measurements obtained from authenticated signature anddollar bills.

Although the present invention has been described in terms of thepresently preferred embodiment, it is to be understood that suchdisclosure is not to be interpreted as limiting. Various alternationsand modifications will no doubt become apparent to those skilled in theart after reading the above disclosure. Accordingly, it is intended thatthe appended claims be interpreted as covering all alternations andmodifications as fall within the true spirit and scope of the invention.

1. An optical probe for detecting a trace chemical material, comprising;a chemical sensor comprising a conductive layer and a plurality ofcolumns on the conductive layer wherein the plurality of columnscomprise a conductive material and neighboring columns in the pluralityof columns are separated by a distance in the range of 10 to 1000nanometers; and a probe head configured to illuminate an incident lighton the plurality of columns in the chemical sensor and to collect anoutput light from the p1urality of columns to detect chemical moleculesof the chemical material.
 2. The optical probe of claim 1, wherein theincident light is a laser beam.
 3. The optical probe of claim 1, whereinthe incident light is scattered by the plurality of columns to producethe output light.
 4. The optical probe of claim 1, wherein the chemicalmaterial is detected by Raman Scattering technique.
 5. The optical probeof claim 1, wherein the conductive material comprises a metallicmaterial.
 6. The optical probe of claim 5, wherein the conductivematerial comprises a noble metal.
 7. The optical probe of claim 1,wherein the neighboring columns in the plurality of columns areseparated by a distance in the range of 10 to 100 nanometers.
 8. Theoptical probe of claim 1, wherein surfaces of the plurality of columnsare configured to adsorb molecules of the chemical material
 9. Theoptical probe of claim 1, wherein a probe head comprises a first opticalfiber configured to transmit the incident light to the plurality ofcolumns in the chemical sensor and a second optical fiber configured tocollect the output light from the plurality of columns in the chemicalsensor.
 10. The optical probe of claim 1, further comprising a spectralanalysis device configured to analyze the output light from theplurality of columns in the chemical sensor to detect the chemicalmaterial.
 11. The optical probe of claim 1, wherein the chemicalmaterial is from a gas, a liquid, or a solid.
 12. The optical probe ofclaim 1, wherein the chemical material comprises a material selectedfrom the group consisting of an explosive material, a harmful chemical,a chemical weapon, a bio-chemical weapon, a nuclear weapon, and anarcotic drug.
 13. The optical probe of claim 1, wherein the chemicalmaterial comprises a hazardous chemical.
 14. The optical probe of claim1, wherein the chemical material is obtained from a patient and thedetection of the chemical material is used to diagnose a disease of apatient.
 15. The optical probe of claim 14, wherein the disease includesa disease selected from the group consisting of lung cancer, breastcancer, stomach cancer, liver cirrhosis, a failing kidney, and ulcercancer.
 16. The optical probe of claim 1, wherein the chemical materialis obtained from a food sample and the detection of the chemicalmaterial is used to inspect quality and safety of food sample.
 17. Theoptical probe of claim 1, wherein the chemical material is obtained froma cargo and the detection of the chemical material is used to inspectmaterials contained in the cargo.
 18. The optical probe of claim 1,wherein the chemical material is obtained from an environmental sampleand the detection of the chemical material is used to monitor pollutantin the environment.
 19. The optical probe of claim 1, wherein thechemical material is extracted from a merchandise and the detection ofthe chemical material is used to authenticate the merchandise againstcounterfeiting.
 20. A method for detecting a trace chemical material,comprising: adsorbing molecules of the chemical material by surfaces ofa plurality of columns in a chemical sensor, wherein the plurality ofcolumns comprise a conductive material and neighboring columns in theplurality of columns are separated by a distance in the range of 10 to1000 nanometers; transmitting an incident light by an optical probehead; illuminating the plurality of columns having surfaces adsorbedwith the molecules in the chemical sensor using the incident light;collecting an output light by the optical probe head from the pluralityof columns having surfaces adsorbed with the molecules; and detectingchemical composition of the molecules in the chemical material using theoutput light.
 21. The method of claim 20, wherein the incident light isa laser beam.
 22. The method of claim 20, further comprising scatteringthe incident light by the plurality of columns to produce the outputlight.
 23. The method of claim 22, wherein the step of detectingchemical composition of the chemical material comprises analyzing theoutput light using Raman Scattering technique.
 24. The method of claim20, wherein the chemical sensor comprises a conductive layer and aplurality of columns are on the conductive layer.
 25. The method ofclaim 20, wherein the conductive material comprises a metallic material.26. The method of claim 25, wherein the conductive material comprises anoble metal.
 27. The method of claim 20, wherein the neighboring columnsin the plurality of columns are separated by a distance in the range of10 to 100 nanometers
 28. The method of claim 20, wherein the step ofilluminating the plurality of columns comprises transmitting theincident light to the plurality of columns in the chemical sensor by anoptical fiber in the probe head.
 29. The method of claim 20, wherein thestep of collecting an output light comprises collecting the output lightfrom the plurality of columns in the chemical sensor using an opticalfiber in the probe head.
 30. The method of claim 20, further comprisinganalyzing the output light from the plurality of columns in the chemicalsensor using a spectral analysis device to detect the chemical material.31. The method of claim 20, further comprising extracting the chemicalmaterial from a gas, a liquid, or a solid.
 32. The method of claim 20,wherein the chemical material comprises a material selected from thegroup consisting of an explosive materials, a harmful chemical, achemical weapon, a bio-chemical weapon, a nuclear weapon, and a narcoticdrug.
 33. The method of claim 20, wherein the chemical materialcomprises a hazardous Chemical.
 34. The method of claim 20, furthercomprising: obtaining the chemical material from a patient; anddiagnosing a disease in the patient by detecting the chemical material.35. The method of claim 14, wherein the disease is selected from thegroup consisting of lung cancer, breast cancer, stomach cancers, livercirrhosis, a falling kidney, and ulcer cancer.
 36. The method of claim20, further comprising: obtaining the chemical material from a foodsample; and inspecting the food quality and safety by detecting thechemical material.
 37. The method of claim 20, further comprising:obtaining the chemical material from a cargo; and inspecting materialscontained in the cargo by detecting the chemical material.
 38. Themethod of claim 20, further comprising: obtaining the chemical materialfrom an environmental sample; and monitoring pollutant in theenvironment by detecting the chemical material.
 39. The method of claim20, further comprising: extracting the chemical material from amerchandise; and authenticating the merchandise against counterfeitingby detecting the chemical material.
 40. A method for detecting a tracechemical material, comprising: adsorbing molecules of the trace chemicalmaterial by surfaces of a plurality of columns on a conductive layer ina chemical sensor, wherein the plurality of columns comprise aconductive material and neighboring columns in the plurality of columnsare separated by a distance in the range of 10 to 1000 nanometers;transmitting a laser beam using a first optical fiber in a probe head;illuminating the plurality of columns having surfaces adsorbed with themolecules in the chemical sensor by the laser beam; scattering the laserbeam by the plurality of columns having surfaces adsorbed with themolecules to produce an output light; collecting the output light usinga second optical fiber in the probe head; and analyzing the output lightusing Raman Scattering technique to detect chemical composition of themolecules of the chemical material.